#include <stdio.h>
int main()
{
	int score = 0;
	scanf("%d", &score);
	switch(score/10)
	{
	case 10:
	case 9:
	case 8:
		printf("A");
		break;
			
	case 7:
		printf("B");
		break;
	
	case 6:
		printf("C");
		break;
	
	case 5:
		printf("D");
		break;
	default:
		printf("E");
		break;
	}
	return 0;
} 
